Harry Potter and the Methods of Self-Modification
by bsen
Summary: After the events of Harry Potter and the Methods of Rationality, Harry and his friends continue their war against an enemy even Voldemort feared. Unfortunately, the world will not wait – or keep them safe – while they mature enough to succeed.
This story is a direct sequel to _Harry Potter and the Methods of Rationality_ (HPMOR), and is written assuming that you have already read HPMOR. (If you read it a long time ago, you might want to refresh your memory for details of chapter 122.) I strongly recommend that you read HPMOR before reading this story, otherwise you will a) have the living daylights spoiled out of you for HPMOR pretty much right away, b) miss a lot of worldbuilding and nuances of prior events that help motivate the characters, c) likely have some difficulties following the characters' thoughts (since they tend to build on techniques and memories they already have), and d) have a disadvantage when it comes to the puzzles because of b) and c).

If you still want to read this story without first reading HPMOR (perhaps you followed the author's advice of trying the first 10 chapters and then giving up if you didn't like it), I recommend that you do the following:

1\. Read a plot summary for HPMOR; the author of _Significant Digits_ has written a nice short one at **anarchyishyperbole dot com slash p slash previously dash on dash harry dash potter dash and dash methods dot html**.

2\. Read the Setting Primer, which should be findable as a story on my profile.

3\. If you have trouble following a character's thoughts while reading, try looking for a nonfictional explanation of any missing principles and/or techniques. This is a long shot since you probably don't know what's missing, but there will probably be an explanation somewhere in the Sequences. Both a freshly edited ebook version of the Sequences and the original posts can be found from **wiki dot lesswrong dot com slash wiki slash Sequences**. Another useful tactic is to go through the chapter titles of HPMOR and look up any that appear to be terms you don't know.

* * *

Based on reader reactions to HPMOR, its disclaimers regarding didactic intent were clearly not strong enough. In an effort to overcome the Illusion of Transparency, I am making my disclaimer stronger. So:

1\. The views of the characters (and this means _any character_ , not just 'villains') are not necessarily the views of the author. And even if they were, that wouldn't mean they should also be _your_ views.

2\. Yes, part of the intent is to present models of ways of thinking and rationalist techniques. This does not mean that the characters' thoughts and beliefs are always correct or even well-reasoned – which again applies to _any_ character. In fact, I will sometimes deliberately make them wrong (or miss important nuances, or not apply a useful technique, or so on). Not all of these errors will be corrected blatantly obviously or right away. It's also quite possible that characters will be wrong in ways that are not deliberate on my part, as I make no claim to being a perfect (or adequate) rationalist myself. It should go without saying that the latter type of error has no guarantee of being corrected at all, although constructive corrections if you believe you've spotted an error of this kind (and double-check first) will be appreciated.

3\. Even when the characters are correct, many of their decisions are based on tradeoffs. The right decision for them in their circumstances might not be the right decision for you in your circumstances.

In short, the point here is to provide a hopefully enjoyable story that also gives you material you can think about and learn from. Please take it in that spirit rather than accepting the characters' thoughts and beliefs unquestioningly.

And of course, there's the other disclaimer: _Harry Potter_ belongs to J. K. Rowling. _Harry Potter and the Methods of Rationality_ is the work of Eliezer Yudkowsky. No one owns the methods of rationality or the methods of self-modification.

* * *

Rationality content note: This story will eventually contain exploration of important insights that can be directly happiness-reducing. If all you care about is your own happiness and you think that the presence of those insights will become sufficiently problematic that you are better off not starting to read this story at all, then don't read it. If you yourself have something to protect, though, then continue…

* * *

Thanks for feedback on a draft of this chapter go to kennyloggins1 and Kronopath.

* * *

 _Surrounded by stone, two voices speak two words…_

 _(in an instant, all would be won)_

… _silhouettes outshine the sun… fire black as night._

* * *

Beneath the morning sky, Hermione Granger tucked her wand away. Harry James Potter-Evans-Verres, standing across from her and still holding Dumbledore's wand, seemed both relieved and perturbed by the purely symbolic vow she'd just made, a fact she filed away with the rest of her current set of mysteries regarding Harry. That set was getting rather large, really.

"Um, so you're not asking me to accept your oath or anything?" Harry said.

Hermione shook her head and laughed. "You already did, Harry. You accepted it the moment you decided to support me in my life choices, whatever they are."

Harry nearly squeaked while stepping back. "Please tell me it's not actually possible to accept oaths without knowing their contents."

"Not for any with magical or legal meaning that I know of, although that's admittedly not very many. But the point was that one of my life choices is to continue being your friend, even though being around you sometimes puts me in situations that are weird and dark and scary. Or other times just surreal."

"Oh."

"Less nervous now?"

"About those phrases I mentioned, no. About your oath, yes." Harry finally put Dumbledore's wand away.

"Good. Because I have some more questions about other life choices I should make soon."

"As long as the answers aren't classified."

"Since I'm going to possibly study Occlumency and possibly make use of a time machine," her voice began to rise, "and possibly _take my O.W.L.S in two months_ , is there anything else you can tell me regarding all of those? I'm already tempted to start drawing up study plans _right now_ so that I can catch up on all the classes I missed – even if I did get better grades than Dumbledore in his first year, I still missed two months of school – and see just how frantically I should be studying, and if that pace is actually possible." _An Acceptable grade isn't acceptable performance._ "And as much as a Time-Turner might help with that, I still need to understand the rules for actually using it in order to account for it in my study plans."

Harry nodded. "Of course. Here's the book I studied on Occlumency. I can get you permission to obtain books on it from the library, but that leaves records, so for now just let me know if you want more books about the subject. If you want to make your knowledge of Occlumency public later, you can, but you can't un-tell a secret so please at least wait until you've decided if you want to make that one." He held the book out with both hands, having reached into his pouch as he was talking.

Hermione stepped forward lightly to take the book, still feeling like the new grace in her movements was somehow both strange and perfectly normal all at once. She flipped it around to read the title – _Occlumency: The Hidden Arte_ – and slipped it into her pouch.

"As for Time-Turners, the summary I gave you is basically all you need to know for simple occasional uses like extra studying, since it doesn't cause a paradox even if you see your Time-Turned self. There's also a pamphlet about them, which includes the explanation for those not in on the secret, and if you want to use them regularly there's a potion to extend your sleep cycle so that it doesn't start rotating in reverse and giving the secret away to everyone. If you have more questions-"

She had taken the pamphlet Harry offered while he spoke, but something was off here. "So Time-Turners are actually _secret_ , rather than just not frequently mentioned, and wizards have potions to alter sleep cycles, but Hogwarts decided to treat your sleep disorder by giving you a _time machine_ instead of a potion. WHY?"

Harry stood in front of her, his mouth opening and closing but not producing any words.

Eventually he began to speak again. "You're right, and I'm an idiot for not noticing that myself. Headmistress McGonagall – back when she was Deputy – would have vastly preferred telling Madam Pomfrey to give me a potion over giving me a Time-Turner. She didn't do that, so she didn't know of such a potion, so they probably don't exist. I haven't actually heard of a potion to shorten sleep cycles, only lengthen them. Unless…"

"Unless?"

"Classified."

"Alright. But you were saying something else about Time-Turners before I interrupted you?"

Harry seemed preoccupied as he continued to speak. "Um. Right. I was saying that if you have more questions about Time-Turners, you can ask me; I suppose you could ask Headmistress McGonagall but I think she'll be rather busy for the foreseeable future. Um, as for O.W.L.S, I'm already working on an O.W.L study plan for myself and I'll show it to you when I'm done. For now I suggest that you start on reading the Occlumency book and deciding if you want to study it, since the preliminary exercises take some effort to pick up and Wednesday is in two days."

"In that case, I suppose I should start on it right away. When do you think you'll have your study plan done?"

"Probably later today."

Harry turned to look out over the Hogwarts grounds, just for a moment, and then hugged her again. A breeze blew some of her curls into his messy hair, and they both laughed together as she ever so carefully hugged him back.

"I'll come by after dinner then. Up here again?"

He nodded and let go of her. "Sounds good."

She let go of him in turn, and waved with one hand as she slid down the ladder from the roof.

* * *

Hermione paused at the top of the stairs out of Harry's office. She felt like she could _run_ straight down the long, slowly winding staircase without falling, an activity that would previously almost certainly have resulted in highly unpleasant injury. For that matter, she had just slid down a ladder with no more difficulty than if it was a playground slide. And she couldn't help but think that this sort of power would be very useful for say, outmaneuvering or outrunning trolls.

As she started down the stairs, her thoughts returned to the other thing she'd been wondering about, the thing she'd started wondering about as soon as she saw Professor Flitwick flying a broomstick towards her in that graveyard.

 _How much more do I have to do to survive?_

She had done everything a good student was supposed to do in order to stay safe. She'd paid attention in all her classes and studied her textbooks and practiced the assigned spells under proper supervision. She'd steadfastly avoided forbidden areas, even the third-floor corridor that apparently wasn't forbidden last year, and always followed the rules of Transfiguration (except for that incident with Harry's experiments). She'd read beyond the required material and participated in Professor Quirrell's armies and taken Harry's suggestions on additional magic items for her protection.

And yet all that hadn't been enough to save her, even under the aegis of the Hogwarts wards, even when she'd correctly identified the evil Professor out of everyone in Hogwarts, and so she had _literally died_.

Harry had resurrected her somehow, giving her the chance to learn from a mistake of that magnitude which most people never got. So far, what she'd been realizing was how much she had to learn.

Following rules and expectations was clearly not sufficient, and neither was going above and beyond expectations in the obvious ways. More magic items hadn't helped when she hadn't taken precautions against them being sabotaged. Knowing more spells and more facts about trolls hadn't helped when the particular troll she faced turned out to be unharmed by sunlight and she couldn't leverage her spell knowledge into _actually keeping the troll from harming her_. Knowing about all sorts of Muggle weapons didn't help her when she didn't have any of them available and couldn't Transfigure them in time. At the time those protections had seemed to be plenty, though, and that was the trap; she had expected her existing precautions to be enough to keep her safe, so she didn't want more resources spent on giving her extra advantages.

On the other hand, Harry's sort of reasoning, full of looking for every advantage and taking extra precautions and disregarding expectations whenever it suited him, also seemed possibly _useful_ but not _sufficient_. He had thought of carrying a magical first aid kit everywhere, even before he had any particular reason (that she knew of, anyway) to suspect an attack. And then he had actually acquired one and managed to use it when an attack occurred.

Yet when Harry had plunged the syringe of oxygenating potion into her neck, she'd recognized it – from a conversation she'd had with Harry about their respective introductions to Diagon Alley, so long ago – and wondered if that action would actually help her. (From having read her parents' human physiology textbooks and considering how quickly she lost consciousness afterwards, she suspected that it might have made things worse instead by _decreasing_ circulation to her brain.) In retrospect, this line of thinking seemed far more useful to have _well in advance of needing the answer_ , when there was time to look things up in the library and work through the problem without anyone's life depending on how long it took to get the result. And this appeared to be a thing Harry hadn't thought of sufficiently far in advance.

Even her new mysterious superpowers weren't enough to keep her alive in this world. Last night, a scarred man with a bright blue eye had popped out of the Floo, wand raised and whirling, and spoke the words of the Killing Curse with his wand aimed at her chest before she'd registered the possibility of a threat. Afterwards Professor Flitwick had introduced the man as Alastor Moody, who had then gruffly explained that he was only checking her for possession by Voldemort, but even though that wasn't an actual attempt on her life it still made the point that no amount of grace or speed would help her until she noticed the threat in the first place. Even if she had had her wand with her she wouldn't have known to raise it before promptly dying _again_.

And that was what she had faced – and lost to – just for existing and being Harry's friend. Now that she had a "heroic" identity of her own, and planned to paint an even bigger target on her back by choosing to do the best thing she could do even if it wasn't the easiest or made her enemies, what would the world throw at her next?

This was why she had asked Harry about investigating her superpowers and acquiring Muggle weapons – she couldn't enjoy her life or help others if she was dead. But would that be enough? Was "enough" even a useful concept for this?

 _What level do I need to reach to survive this world, let alone improve it?_

* * *

Hermione's books had been disturbed. It was immediately obvious why, since she had last left them interspersed with library books, but that was still the first thing she noticed upon seeing her bed in the Ravenclaw dorm – even before all the cards on her nightstand, or the (probably enchanted to last) flowers surrounding her bed.

She reached down and neatly piled the flowers on one side, clearing the way for her to pick up the note atop the largest stack of books on her bed.

 _Miss Granger,_

 _My deepest thanks for saving us from another war._

 _As you have no doubt noticed by now, I collected the books you had signed out from the Hogwarts library at the time of your death. Since you will be staying in Hogwarts for at least part of the summer, you are of course welcome to pick up any of those books if you wish to resume reading them._

 _(Summers are an excellent time to borrow books in high demand, by the way – Hogwarts library lending policies remain the same but far fewer students are around to take advantage of them.)_

 _-Madam Pince_

Hermione balanced on the toes of her right foot as she considered the note.

She would return to the library soon enough, but probably wouldn't be after quite the same books anymore. Before she had been reading whatever caught her interest, but right now she had specific problems to solve, and solve fast. Like learning four years of material in two months.

But why did Harry want her to get her legal majority so fast? What plan did he have that was worth, at least in his mind, getting Acceptables on her O.W.L.S? What had he gotten himself into that involved Unbreakable Vows and phrases like "the end of the world and its magic"? Last time she checked, he didn't want to destroy the world either; if anything, he wanted to make it a better place to live.

Harry had good intentions with all his plans, he didn't want to hurt anyone and often wanted to help, but he didn't always go about it in a very nice way or get the best results. Sometimes he did truly spectacular things like getting Professor Snape to apologize in front of the whole Great Hall, other times he did spectacularly bad things like scaring Padma Patil by pretending to be a ghost, and yet other times he did deeply strange things like trying to scare Lucius Malfoy immediately after going sixty thousand Galleons in debt to him. (Honestly, she wasn't quite sure what Harry had _intended_ to accomplish with that last one.) Overall, he was a well-intentioned force of chaos to anyone who didn't know what he was planning and why.

And it had occurred to her that letting a well-intentioned force of chaos arrange things for her – and possibly the whole world, if she had worked out the scale of his plans correctly – was not necessarily the best thing she could do, even if Harry was letting her choose whether to use the things he arranged. Would getting lower marks on her O.W.L.S now prevent her from taking important classes later? Would his other plans have other problems? The advantages he'd already given her alone… the Time-Turner seemed clear-cut enough, if it was safe enough to use for extra studying or treating his sleep disorder it was safe enough to use as an emergency precaution, but he had told her that he couldn't risk himself adventuring and then given her a _unique irreplaceable Deathly Hallow_ whose power seemed rather useful for _getting out of adventures_. He could get himself another invisibility cloak, but this still struck her as giving up an advantage he might need.

She could ask those questions now, but she couldn't work out the answers unless she knew what he was planning. She couldn't decide _for herself_ what the best thing she could do was until she knew, and relying on Harry's judgement for that was rather suspect, mysterious young wizard or not. Sometimes being a good person, or a good friend, meant telling a friend that you thought their plan was flawed or not letting them carry it out.

But Harry _couldn't tell her_ what his plans were unless and until she became an Occlumens. Even thinking about her own speculations on the nature of her powers and her own plans was hazardous for as long as those thoughts could be pulled from her mind.

And she refused to live her life with restrictions on what she was allowed to think about, or with fear of drawing the attention of a Legilimens keeping her from doing the best she could do. That settled the matter as far as she was concerned; she was going to learn Occlumency regardless of it being a "sixth-year thing".

She leapt nimbly into her usual spot on her bed, tucked the note into her pouch, and settled in to read.

* * *

 _If that particular development had happened to a slightly different mind, everyone would have died._

* * *

I am not guaranteeing any schedule for updates at this point; if you keep refreshing the page you will most likely be disappointed on any given refresh. You can be notified of updates through the FFN alert system or through update posts on Reddit ( /HPMOR and most likely /rational).


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